zeutschel



March 17, 1964 H. M. ZEUTSCHEL SCALING DEVICE Filed Dec. 6. 1961 HEINZ M. ZEUTSCHEL INVENTOR.

ATTORNEY United States Patent 3,125,064 SCALING DEVICE Heinz M. Zeutschel, Arlington, Mass., assignor to Itek Corporation, Lexington, Mass., acorporation of Delaware Filed Dec. 6, 1961, Ser. No. 157,446 3 Claims. (Cl. 116-124) This invention is directed to a scaling device and in particular to a device for calibrating a knob in relation to the angular position of the knob.

There are many examples of mass produced equipment that includes at least one element subject to variations in physical characteristics. Although each element is made to close tolerances, variations require individual calibration of each piece of equipment. For example, in a microfilm enlarger, variable magnification is obtained by moving the lens through distances proportional to the focal length of the lens. However, the focal length of a lens varies from lens to lens of the same type by plus or minus three percent. The distance the lens is moved must then be varied to accommodate to the individual lens focal length. Heretofore, in order to account for variations in focal lengths, it has been necessary to specially make for the particular lens a knob with calibration marks which had been calculated for the particular focal length. Another method was to move the lens for sequential degrees of magnification and individually mark the scale. These solutions have not been satisfactory because they require the performance of precision manual tasks that are expensive and time consuming.

In accordance with the invention there is provided a scaling device comprising a rotatable body having a conic surface and being mounted to rotate about a fixed axis. There is provided a strip having a surface complementary to the conic surface of the body. The strip is provided with graduation marks spaced longitudinally on the strip. Means are provided for attaching the strip to and along the surface of the body at an adjustable location relative to the fixed axis of the body. The circumferential spacing between the graduation marks is varied, thereby with respect to the fixed axis.

The strip is premarked and then mounted to the conical surface of the body. The strip is moved axially along the conical surface so that the marks will intercept smaller or larger arcs depending upon its axial position along the conical surface of the body.

For a better understanding of the invention, reference is made to the following detailed description which refers to the accompanying drawing, wherein an isometric view of the scaling device embodying the invention is illustrated.

In the drawing, the numeral designates a knob in the form of a shell having a conical surface 12. The conical surface 12 is the lateral surface of a frustrum produced by cutting a right circular cone with parallel planes at right angles to the cone axis of rotation. The

knob 10 is affixed to the end of a shaft 14 passing through and rotatably mounted on a panel 16. By way of example, the panel 16 can be considered as a part of microfilm enlarger with the other end of the shaft 14 coupled to the lens moving mechanism.

A strip 18 having a surface complementary to that of the knob 10 is provided with premarked graduation marks 20 spaced along the longitudinal axis of the strip 18. Bolts 22 are passed through the longitudinal axis of the strip 18 at both ends and through symmetrical slots 26 cut through the conical surface 12 of the knob 10. Only one of the slots 26 is shown for the sake of clarity. The bolts 22 are drawn into nuts, not shown, on the under-side of the conical surface 12. A reference mark 30 is aflixed to the panel 16 in juxtaposition with the graduation marks 20.

The strip 18 is moved axially on the lateral surface 12 of the knob 10 by sliding the bolts 22 in the slots. The longitudinal axis of the strip 18 extends in a plane perpendicular to the axis of the knob 10. The circumfer ence of the circle made by the intersection of the plane and the lateral surface 12 varies with the position of the plane along the axis of the knob 10. An arc length along the circumference varies in proportion to the position of the plane while the angle about the center of the circumference subtending the circumference remains constant. Rotation of the knob 10 through a given angle can be represented by varying arc lengths depending upon the position of the plane. The varying arc lengths are measured between adjacent graduation mark 20 intersecting the reference mark 30. When the desired arc length for a given angle of rotation is achieved the strip 18 is affixed to the lateral surface 12 of the knob 10 by tightening the bolts 22 and nuts. Thus, the relation is established between the spacing of the graduation marks 20 and the change in angular position of the knob 10 for the desired arc length. The relative angular disposition of the slots 26 is selected so that the circumferential length of the strip 18 is held constant through the range of adjustment. However, the angle subtended by the strip varies with its adjustment.

In the microfilm enlarger previously described, as the lens is moved, the lateral surface of the knob rotates through an arc length proportional to the distance the lens is moved because the distance varies from different lens of the same type, the arc length will vary proportionally. To calibrate the knob to accurately indicate the degree of magnification for a particular lens position, the operator need now only slide the strip until the graduation mark corresponding to the degree of magnification intersects the reference mark and afiixes the strip to the knob.

While there has been described what is at present considered to be the preferred embodiment, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the invention. Therefore, the invention should not be deemed to be limited to the details of what has been described by way of example but rather it should be deemed to be limited only to the scope of the appended claims.

What is claimed is:

1. A scaling device, comprising:

a rotatable body having a tapered circumferential surface and being mounted to rotate about a fixed axis;

a scale element having a surface complementary to that of said body and. being provided with graduations spaced oircumferentially of said scale element; and

means for attaching said sca le element to the surface of said body at an adjustable location relative to and along said fixed axis,

thereby to vary the circumferential spacing between said marks with respect to said fixed axis.

2. A scaling device, comprising:

a rotatable body having a conic surface and being mounted to rotate about a fixed axis;

a strip having a surface complementary to that of said body and being provided with graduation marks spaced longitudinally thereof; and

means for attaching said strip to the surface of said body at an adjustable location relative to and along said fixed axis,

thereby to vary the circumferential spacing between said marks with respect to said fixed axis.

3. A scaling device, comprising:

a hollow rotatable body having a comic surface and being mounted to rotate about a fixed axis, said body being provided with slot shaped apertures in said surface communicating between the exterior and interior of said body;

a strip having a surface complementary to that of said body and being provided with graduation marks spaced longitudinally thereof; and

means, including threaded elements passing through said strip and apertures and nuts in threaded engagement with said threaded elements, for attaching said References Cited in the file of this patent UNITED STATES PATENTS Kahn Aug. 18, 1942 Mucher et al. Oct. 29, 1957 

1. A SCALING DEVICE, COMPRISING: A ROTATABLE BODY HAVING A TAPERED CIRCUMFERENTIAL SURFACE AND BEING MOUNTED TO ROTATE ABOUT A FIXED AXIS; A SCALE ELEMENT HAVING A SURFACE COMPLEMENTARY TO THAT OF SAID BODY AND BEING PROVIDED WITH GRADUATIONS SPACED CIRCUMFERENTIALLY OF SAID SCALE ELEMENT; AND MEANS FOR ATTACHING SAID SCALE ELEMENT TO THE SURFACE OF SAID BODY AT AN ADJUSTABLE LOCATION RELATIVE TO AND ALONG SAID FIXED AXIS, THEREBY TO VARY THE CIRCUMFERENTIAL SPACING BETWEEN SAID MARKS WITH RESPECT TO SAID FIXED AXIS. 